ESTUARIES IN SOUTH AFRICA

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MGENI ESTUARY: Catchment Characteristics

Main Rivers and tributaries
The Mgeni River rises in the Natal Midlands and has been largely modified by human activities, mainly intensive agriculture, forestry and urban settlements. (Ref.2).
1978 (Ref.1): Catchment characteristics: "AREA - Various refrences provided a range from 4 385 km² to 5 850 km². RIVER LENGTH - 230 km to 235 km.
Dams
Dam	Constructed	Capacity
Henley Dam	1942
Nagle Dam	1950	20,8 x 10⁶m³
Midmar Dam	1963	172 x 10⁶m³
Albert Falls Dam	1975	261 x 10⁶m³
Inanda Dam		241,7 x 10⁶m³
"The Mgeni is the most important water supply for both Durban and Pietermaritzburg" (Ref 1).
River run-off
Mean annual run-off - 707 x 10⁶m³.(Ref 1).
Geomorphology
"The original source of the pink sands in the Mgeni Estuary, is supposedly the Archaean granites in the Valley of a thousand hills. The bedrock below the estuary is weathered and fractured shale, with dolomite intrusions" (Ref 1).
Geology
"In the catchment, the river traverses a whole variety of rocks of different geological characteristics. The Archaean granites (in the Valley of a Thousand Hills) are said to be the source of the pink sands in the Estuary. Orme described bedrock below the estuary as shale which was “fractured and weathered towards the surface with some dolerite intrusions. At the Athlone bridge, bedrock was found to be 52 m below mean sea level, although reported to be at 67 m below mean sea level at another locality. At the Connaught bidge bedrock lay at a depth in excess of 28 m below mean sea level" (Ref 1).